The present invention relates to a hydro-pneumatic positioner for the support, transport and lifting or lowering of a trailer provided with a cradle, having special adapters for supporting a wing engine and to be used for the removal or installation of an engine, in particular, for aeroplanes of the types known under the names: Douglas D.C.10, Airbus A 300 or for other similar intended purposes.
Several systems and devices are already known for the installation or removal of wing engines. Said known systems present limited safety and low protection reliability for the operators using these systems.
The workers not only must work in uncomfortable positions in which they are hampered by the structures which are part of the equipment, but they also work under very high impending loads, so that wrong maneuvres and/or damages in the equipment can cause very serious accidents. The operations to be performed by the devices, known to date, are long, very fatiguing and require considerable preparatory operations before the installation or removal of an engine. These known systems become less and less acceptable, in particular, in airplane engines, with respect to the safety, since any wrong maneuvre can expose men and things to incalculable risks.
One such device is a bridge-crane used in conjunction with sling hooks. The use of such an equipment requires normally the previous removal of the whole engine cowling. Further the workers on the bridge crane and those who operate near the ground must cooperate together at a considerable distance from each other so that the maneuvres require much time and labour in order to be performed in a correct and strict perfect collaboration; they also cause high stress and fatigue in the interested personel. The removal or installation of the wing engines of the like present thus always a poor reliability in the attaining of perfect results; it requires much time and labor.
Another known device is based on the commonly called "Boot Strap System". This device does not require the removal of the engine cowls, because it is designed to operate from the underside of the engine, so that it requires only the use of a frame for holding in open position by means of supporting members, directly the pair of the two halves of the shell forming the central portion of each cowl, and indirectly the pairs of two shell halves forming the front and rear portions thereof.
For such a purpose to the pylon supporting the wing engine and which is integral with the wing, are fastened lateral hoists, the chains or ropes of which are hooked to connectors arranged on the engine body. After the wing engine has been duly provided with forward adapters and with a rear positioning pin and the respective mounting bolts have been removed, the hoists are manually operated from the lower side by the respective operators, who thus work still under the risk of an enormous impending load and who must also work with the maximum concentration so as to able to perfectly coordinate all their movements, meanwhile other operators provide to screw or unscrew the bolts and to direct the whole operation.
The installation is a particularly delicate operation, since, as it is well known to the persons skilled in the art, it is necessary to obtain the exact matching between the bolt holes arranged on the engine and those arranged on the pylon of the aircraft before the insertion and the screwing down of said mounting bolts, also taking in due consideration that the threaded holes of the rear bolts are provided on a rocking support member so that this operation becomes still more difficult to perform.
It also well known that when the mounting bolts are not screwed so as to come into perfect register with the hole axes, internal stresses can be generated which can promote the bolt breakage, which could also cause the disjunction of the engine from the pylon.